A holographic recording medium for recording data by holography has been already invented (e.g. see JP-A-2004-029476). This holographic recording medium is a photosensitive recording medium which is formed in such a manner that a holographic recording layer made of a photosensitive material is provided on a disk type support. Since data are multiplexedly recorded as interference fringes of laser light into a multilayer on the holographic recording medium, the holographic recording medium can have a larger data recording volume than that of a DVD which was heretofore a popular recording medium. When light is exposed to the holographic recording layer or dust is deposited on the holographic recording layer, the performance of the holographic recording layer of the holographic recording medium is affected adversely. For this reason, the holographic recording medium is handled after received in a cartridge having a light-shielding function and a dust-proof function (e.g. see JP-A-2003-317422 (corresponding to US 2003/0198177 A1)).
In the invention described in JP-A-2004-029476, the holographic recording medium is received in a cartridge similar to a cartridge of a DVD-RAM. This cartridge is formed out of a material small in transmittance of light rays in a wavelength range in which the holographic recording layer is affected by the light rays. Although JP-A-2004-029476 did not give any description on the detailed configuration of the cartridge, it may be conceived that the cartridge has the same configuration as that of a cartridge described in JP-A-2003-317422 (corresponding to US 2003/0198177 A1).
In the invention described in JP-A-2003-317422 (corresponding to US 2003/0198177 A1), the cartridge is made of a material capable of blocking a sensitive color in the holographic recording layer. Moreover, a sponge-like shielding material is attached to a joint of a movable portion for exposing the holographic recording medium to the outside. In addition, in the description, the cartridge is provided with a cartridge body for receiving a recording medium therein in a desirably rotatable state, an opening provided in the cartridge body and for exposing part of the recording medium to the outside, and a shutter for opening/closing the opening.